The relation relates to a sensor which gives an indication of a cant angle by means of an output from a resolver.
Cant angle sensors which are used to give an indication of the tilt of a land vehicle are well known in the prior art. A pendulum which is suspended for angular motion seeks a vertical null position as the tilt of the sensor is changed, and the pendulum may be attached to the shaft of a resolver which develops an output signal indicative of this tilt angle. Because the resolver shaft is delicately balanced, the pendulum is prone to oscillations about a vertical null point when a new null is being sought. Various damping means such as magnets in combination with a ferromagnetic pendulum have been used to limit these oscillations. The force exerted by the magnets on the pendulum requires the pendulum to be heavy so that the damping force of the magnets is not so great that the pendulum will not seek a true vertical null. Brush contacts rubs on the resolver shaft to couple signals developed in the resolver to output terminals. These brush contacts inherently exert a frictional force on the resolver shaft. A very light brush force often results in noise and erroneous signals being generated, while a heavier force increases the turning resistance of the shaft requiring the pendulum to be even larger. In an attempt to avoid the use of brush contacts, hairsprings have been provided to conduct output signals from the rotor coils to output terminals. These hairsprings are never without an elastic memory however, and this memory exerts a restoring force on the rotor shaft to give a null signal which is not true. A torqueless or brushless resolver can be built utilizing pure electromagnetic coupling between the rotor shaft and the resolver output leads, but the cost of such a device is too high to be a commercially satisfactory alternative.